Obama calls Egyptian, Israeli leaders

US President Barack Obama has called Egypt's Mohamed Morsi and Israel's Benjamin Netanyahu amid efforts to broker a ceasefire between Israel and Hamas in Gaza, the White House says.

During his conversation with the Egyptian president, Obama, who was in Cambodia on a three-nation tour in South-East Asia, "underscored the necessity of Hamas ending rocket fire into Israel", a White House statement said.

"President Obama then called Prime Minister Netanyahu of Israel, and received an update on the situation in Gaza and Israel," the statement added.

A sixth day of Israeli strikes on Monday killed 24 Palestinians, taking the Gaza death toll past 100 as UN chief Ban Ki-moon joined efforts to broker a truce to end the worst violence in four years.

As Ban arrived in Cairo to push for a ceasefire, Hamas chief Khaled Meshaal said his movement was committed to efforts to secure a truce with Israel, but insisted the Jewish state must lift its six-year blockade of the Gaza Strip.

Egypt is leading efforts to mediate the truce, chairing marathon indirect negotiations in Cairo between Meshaal and an Israeli envoy.

"In both calls, President Obama expressed regret for the loss of Israeli and Palestinian civilian lives, and agreed to stay in close touch with both leaders," the White House statement said.

Egypt's Islamist administration, which has close ties with Hamas, recalled its ambassador on Wednesday in protest at the Israeli operation, which began with the targeted killing of a top Hamas military commander.

Morsi, an Islamist elected in June after the overthrow of Hosni Mubarak in 2011, has promised to take a harder line on Israel than his predecessor, who was accused of doing little to stop the Jewish state's devastating assault on Gaza in December 2008-January 2009.

The United States, Israel's closest ally, has backed Netanyahu's calls for Hamas to put an end to rocket attacks into Israel in response to the military campaign.

Obama spoke last Wednesday by telephone with Netanyahu and urged him to "make every effort to avoid civilian casualties", while stressing Israel's right to defend itself from Hamas's attacks.